January 12, 2006

Broken ice dam blamed for 300-year chill?

I got into this subject after watching a terrific 2-hour special on the "Little Ice Age" during medieval times on the History Channel (official title: "Little Ice Age: Big Chill." ) You read and hear about various political and social forces during the so-called "Dark Ages," the Enlightenment, the American and French Revolutions, but here I am a weather geek, but previously I knew nothing about the climate issues that precipitated some of that social unrest (not to mention the implications for public health and nutrition).

So this thing in New Scientist caught my attention, but if you watch the same show I did, you probably won't be so quick to blame an ice dam as a clear cause/effect thing (the article below tempers totally direct causality as well). The TV program outlined a number of interrelated theories as to why the climate shifted during those centuries, not the least of which was a big volcanic eruption in Indonesia toward the end that kept summer from arriving one year. In the show, I was most fascinated by the early part of the period rather than the later part, because the social effects were so dramatic. I could imagine trying to deal with such inexplicable changes myself.

I remember seeing an unusual (to me) bit in the film version of Virginia Woolf's "Orlando," when there was this strange ice party/carnival in England, and the crew of a Russian or Slavic boat was forced to winter there because the sea-going boats were iced in.

Also, I've been learning a bit more about these ice dams from living last semester in Missoula, Montana, an area that once was a massive freshwater lake held in place by an ice dam as well, I've been told. When that dam busted, it made a 500-foot wave that ran all the way to the Pacific, according to folks there. They may have been joshing a newbie, but I bought it.

Broken ice dam blamed for 300-year chill

14:21 10 January 2006 NewScientist.com news service Kurt Kleiner

A three-century-long cold spell that chilled Europe 8200 years ago was probably caused by the bursting of a Canadian ice dam, which released a colossal flood of glacial meltwater into the Atlantic Ocean.

Two new papers, using different computer models, show that the massive freshwater flood accounts for evidence of the sudden climate change, which cooled Greenland by an average of 7.4°C, and Europe by about 1°C. It was the most abrupt and widespread cool spell in the last 10,000 years.

[...]

In 1999 Don Barber, a geologist now at Bryn Mawr College in Pennsylvania, US, and colleagues suggested that the cooling was caused by flooding by glacial meltwater. Geological evidence shows that by about 11,000 years ago, retreating glaciers had left two huge freshwater lakes sprawling over Central Canada and parts of the northern US, bigger than all of today's Great Lakes combined.

Eventually, the lakes broke through an ice sheet that served as a dam and drained into Hudson Bay, and from there into the North Atlantic (Nature, vol 400, p 344).

[...]

"Strong confirmation"

In the new papers, one in the Proceedings of the National Academy of Sciences and the other in the current Quaternary Science Reviews, two teams of researchers using different computer models say that both models show that such a freshwater flood could shut down ocean circulation in a way that is consistent with temperature data from the time.

[...]

The work could have implications for the modern climate. Some researchers suggest that global warming and glacial melting might one day change ocean salinity enough to cause a similar disruption in ocean currents.

BTW, it was on the History Channel that I watched that documentary. Here's the listing for the next showing of it, on January 23rd, twice that day, times depending on your time zone. They've got the DVD for sale too. Little Ice Age: Big Chill DVD Climatologists reveal what happened, and debate whether a similar cataclysm is in store for the 21st century. See how a few small degrees of difference changed the face of the world for centuries.

Scientists call it the Little Ice Age--but its impact was anything but small. From 1300 to 1850, a period of cataclysmic cold caused havoc. It froze Viking colonists in Greenland, accelerated the Black Death in Europe, decimated the Spanish Armada, and helped trigger the French Revolution. The Little Ice Age reshaped the world in ways that now seem the stuff of fantasy--New York Harbor froze and people walked from Manhattan to Staten Island, Eskimos sailed kayaks as far south as Scotland, and "the year without a summer" saw two feet of snow fell on New England one June and July.

Could another catastrophic cold snap strike in the 21st century? Leading climatologists offer the latest theories, and scholars and historians recreate the history that could be a glimpse of things to come. Face the cold, hard truth of the past--an era that may be a window to our future.

Tune In:Monday, January 23 @ 10am ET/PT

Not so long ago, civilization learned that it was no match for just a few degrees drop in temperature. Scientists call it the Little Ice Age--but its impact was anything but small. From 1300 to 1850, a period of cataclysmic cold caused havoc. It froze Viking colonists in Greenland, accelerated the Black Death in Europe, decimated the Spanish Armada, and helped trigger the French Revolution. The Little Ice Age reshaped the world in ways that now seem the stuff of fantasy--New York Harbor froze and people walked from Manhattan to Staten Island, Eskimos sailed kayaks as far south as Scotland, and two feet of snow fell on New England in June and July during "the Year Without a Summer". Could another catastrophic cold snap strike in the 21st century? Leading climatologists offer the latest theories, and scholars and historians recreate the history that could be a glimpse of things to come. Face the cold, hard truth of the past--an era that may be a window to our future. TVPGcc

Credits

Privacy Policy

Privacy Policy for Google Ads

We use third-party advertising companies to serve ads when you visit our website. These companies may use information (not including your name, address, email address, or telephone number) about your visits to this and other websites in order to provide advertisements about goods and services of interest to you. If you would like more information about this practice and to know your choices about not having this information used by these companies, click here.